The disclosure relates to a method of manufacturing an electro-optical device with which a plurality of electro-optical panels are manufactured by attaching a first substrate to a second substrate and dividing the attached substrates into a plurality of sections.
In an electro-optical device such as a light-transmissive liquid crystal device, a liquid crystal panel which is an electro-optical panel configured by filling liquid crystal between two substrates formed of glass substrates or quartz substrates may be contained in a packaging case.
The liquid crystal device can be made to display an image by arranging switching elements such as thin-film transistors (TFTs) and pixel electrodes on one substrate of the liquid crystal panel in a matrix, arranging counter electrodes on the other substrate, and varying an optical response of a liquid crystal layer interposed between both substrates in accordance with an image signal.
A TFT substrate on which the TFTs are arranged and a counter substrate which faces the TFT substrate may be separately manufactured. The TFT substrate and the counter substrate may be formed by laminating a semiconductor thin film, an insulating thin film or a conductive thin film having a predetermined pattern on, for example, a quartz substrate. The semiconductor thin film, the insulating thin film or the conductive thin film may be formed by repeatedly performing a film forming process and a photolithography process.
The TFT substrate and the counter substrate may be attached with high precision (for example, an alignment error of 1μ or less) in a panel assembling process. In this panel assembling process, for example, alignment films which align liquid crystal molecules along the surface of the substrate are formed on surfaces of the TFT substrate and the counter substrate, both of which contact the liquid crystal layer.
Thereafter, the alignment films are subjected to a rubbing process for determining the arrangement of the liquid crystal molecules when a voltage is not applied. Next, in a liquid crystal dropping method, a seal material formed of an adhesive is formed on edges of a plurality of TFT substrates configured in a large substrate and a predetermined amount of liquid crystal is dropped onto liquid crystal filling regions of the TFT substrates surrounded by the seal material.
Next, in the large substrate assembling method, a first large plate including the plurality of TFT substrates and a second large plate including the plurality of counter substrates are attached to each other using the seal material or the adhesive for temporary fixation such that the TFT substrates and the counter substrates face each other. Thereafter, the attached substrates (hereinafter, referred to as a structure) are divided into a plurality of sets of the TFT substrate and the counter substrate which face each other and have a chip shape.
Next, a flexible printed circuit (FPC) for connecting an electronic device such as a projector to a liquid crystal device may be connected to an external connection terminal of the TFT substrate and, as a result, a liquid crystal panel is manufactured.
Thereafter, the liquid crystal panel is contained and fixed in a packaging case such that a liquid crystal device is manufactured. The manufactured liquid crystal device is provided in an electronic device such as a projector.
Examples of a method of dividing the structure into the plurality of sets of the TFT substrate and the counter substrate having the chip shape include a dicing process with excellent workability, high processing accuracy and outer shape accuracy necessary for the divided TFT substrate and counter substrate.
However, if the substrate is divided by passing a blade through the counter substrate in a thickness direction using the dicing process, a wiring line such as an external connection terminal or a driver circuit formed on the TFT substrate may be damaged by the blade, and consequently the manufacturing yield may deteriorate.
Accordingly, a method of dividing the structure into the plurality of sets of the TFT substrate and the counter substrate having the chip shape by a scribe/break process has been generally suggested and used.
In the scribe/break process, first, scribe lines are formed at division positions of the first large substrate including the plurality of TFT substrates and the second large substrate including the plurality of counter substrates using a scribe cutter by a scribe process.
Next, cracks passing through the substrates are generated in the thickness direction of the first large substrate and the second large substrate along the scribe lines by a break process of pressing the positions of the substrates facing the scribe lines, that is, the position of the second large substrate, including the plurality of counter substrates, facing the scribe line of the first large substrate after the scribe line has been formed on the first large substrate including the plurality of TFT substrates and the position of the first large substrate facing the scribe line of the second large substrate after the scribed line has been formed on the second large substrate. Finally, the structure is divided into the plurality of sets of the TFT substrate and the counter substrate having the chip shape using the generated cracks.
Japanese Patent Application Laid-Open Publication No. 2006-98632 discloses a technology for preventing division portions of the TFT substrate or the counter substrate of the liquid crystal panel after division from being damaged due to the pressure applied from the scribe cutter to the structure in the scribe process by including a jig member for supporting the substrate in a scribe device for performing the scribe process in the scribe/break process.
However, in the method of dividing the structure into the plurality of sets of the TFT substrate and the counter substrate having the chip shape by the scribe/break process, it may be difficult to form the scribe lines in a straight line shape in plan view with respect to the division positions of the first large substrate including the plurality of TFT substrates and the second large substrate including the plurality of counter substrates. That is, after the scribe process, the scribe lines may be formed on the large substrates so as to have a zigzag shape in plan view.
When the cracks are generated along the scribe lines by the break process, it is difficult to vertically generate the cracks in the thickness direction of the substrates at all the division positions.
The division end faces of the TFT substrate and the counter substrate of the liquid crystal panel after the division has been performed by the scribe/break process may vary in shape in plan view and may vary in shape in the thickness direction according to the division positions. For example, the cross-sectional shapes of the TFT substrate and the counter substrate formed by the division end faces may vary. Thus, it is difficult to ensure the outer shape accuracy necessary for the TFT substrate and the counter substrate.
As a result, when the liquid crystal panel is contained in the packaging case, for example, when the opposite end faces of the counter substrate are brought into contact with opposite walls of a containing chamber of the packaging case and the liquid crystal panel is contained in the containing chamber, the liquid crystal panel may become misaligned in the packaging case due to a counter substrate having a different cross-sectional shape and thus the manufacturing yield of the liquid crystal device may decrease.